The present invention pertains to systems and methods for thermally heating and cooling fluid solutions. More particularly, the present invention pertains to systems and methods for selectively heating and cooling samples held in a plurality of through-hole wells of a holding plate. The present invention is particularly, though not exclusively, useful as a system for selectively heating and cooling samples held in fluid solutions in through-hole wells of a holding plate by establishing effective thermal communication through a metallic coating that extends from the surface of the holding plate into the lumen of each well.
Specimen samples may be required to be heated or cooled for various applications. Some applications, however, may require specimen samples to be subjected to thermocycling which involves alternating from high temperatures to lower temperatures for a particular length of time at each temperature. For example, one such application is the amplification of nucleic acid sequences in a process known as polymerase chain reaction (PCR).
Depending on the equipment that is being used, and the particular procedure (application) that is being followed, the heating and cooling of specimen samples will require several considerations. Specifically, one consideration includes the length of time for the change in temperature to occur. This is so because it may be desirable for a temperature change to occur either as rapidly as possible or with very slow, controlled variations. An additional consideration is maintaining a substantially uniform temperature among the samples which are to be heated and cooled. Also, it may be very important for all the samples to experience the same change in temperature at the same time. To further these considerations, it is important to have an efficacious transfer of heat from a heat transfer device to the samples. This is so, regardless of whatever tray, plate or other holding device is being used for holding the samples.
It is well known that holding plates are widely used for holding large numbers of small samples for use in various testing procedures. When temperature control, or predetermined temperature variations are required for the testing or analysis of samples, there must be effective thermal communication between some type of heat transfer device and the samples. For instances wherein the samples are being held in the many through-hole wells of the holding plate, the structure of the holding plate can become important. This situation can become particularly complicated when the material of the holding tray is a poor thermal conductor and access to samples is difficult because the diameters of the through-hole wells in the holding plate are very small.
In light of the above, it is an object of the present invention to provide a system and method for selectively heating and cooling samples in a solution in through-hole wells of a holding plate by establishing an effective thermal communication between the surface of the holding plate and the samples which are to be heated and cooled. Another object of the present invention is to provide a system and method for selectively heating and cooling samples with minimal effect from ambient environmental conditions. Yet another object of the present invention is to provide a system and method for selectively heating and cooling samples which is effectively easy to use, relatively simple to manufacture and comparatively cost effective.
A system and method for selectively heating and cooling samples in a solution includes a holding plate having two substantially flat, rectangular-shaped opposing surfaces, and a plurality of through-hole wells for holding the samples and solution. With the wells being formed through the holding plate between the opposing surfaces, each well has a first end and a second end with a preferred aspect ratio of preferably greater than about 5:1. Further, each well of the present invention is generally cylindrical-shaped and it preferably has a diameter of less than approximately five hundred microns.
For the present invention, a metallic coating is positioned, using vapor deposition techniques (e.g. sputtering), on one of the opposing surfaces of the holding plate. Importantly, as a result of the vapor deposition process, this coating will extend into the lumen of each well to contact a solution that is being held in the wells. For the present invention, it is envisioned that the metallic coating will extend a distance of approximately one and one half well diameters (e.g. approximately 750 microns) or as much as two to three diameters into the lumen of each well for contact with the solution in the wells. In an alternate embodiment of the present invention, it is contemplated that the metallic coating can be disposed on both opposing surfaces of the holding plate, and into each well lumen from both ends of the through-hole wells. In either case, since the well diameters are very small, this metallic coating is disposed on the holding plate using any suitable vapor deposition techniques.
For the present invention, a heat transfer device is thermally connected to the metallic coating to establish thermal communication between the heat transfer device and the metallic coating on the surface of the holding plate. Since the metallic coating extends into the well lumens, and is in contact with the solution held in these wells, this coating interconnects the heat transfer device with the solution in the wells. When activated, the heat transfer device will heat or cool the solution and the samples, as desired, via the metallic coating.
In addition to the holding plate, the system of the present invention can include a cap member that is engageable with the holding plate to cover at least one of the opposing surfaces of the plate. As envisioned for the present invention, the cap member will protect the solution and the samples from any ambient environmental conditions, such as evaporation or condensation. Further, by covering the holding plate with the cap member, any spilling or leaking of the solution from the wells can be prevented.
In the operation of the present invention, the wells of the holding plate are first filled with samples in a solution. When the heat transfer device is activated, a thermal communication is established between the device and the solution through the metallic coating on the holding plate. Via the metallic coating, the samples and solution can be heated or cooled, as is necessary for an intended purpose.